I've found a design of a possible Unidad Popular flag, and I made the drawing which might be correct. Santiago Gómez, 9 August 2006
The black saltire vertically represent the letters "VXA," which stand for "Vote (For) Allende," where an "X" is what a voter writes on the ballot. Alex Garofolo, 29 January 2016
| image by António Martins and Santiago Gómez, 9 August 2006
There is also a flag/design from the 1964 presidential campaign; it is drawn exactly the same but without the "U.P." initials but the "V.X.A." ("Vote For Allende" / "Vota para Allende") is the same. Santiago Gómez, 9 August 2006
The Unidad Popular was formed in 1969, which probably explains why this flag does not carry the "U.P." initials. Allende contested the presidency in 1964. Alex Garofolo, 29 Januar 2016
MAPU OC (MAPU Obrero Campesino) a Worker-Farmer splinter group)
Aftermath of the 1973 Coup d'état:
During the military dictatorship that ruled after the 1973 coup d'état, all parties (and their members) that comprised the U.P. were outlawed by Decreto Ley (Decree Law) No. 77 of 8 October 1973. The U.P. leadership still existed in exile. However, in 1979, with the fractioning of the PS (the UP's driving force), the U.P. finally ceased to exist in 1981. Esteban Rivera, 9 March 2016